Display device

• US 5,760,851 A
• Filed: 05/24/1996
• Issued: 06/02/1998
• Est. Priority Date: 11/28/1993
• Status: Expired due to Fees

• Current Assignee: Smartlight Ltd.
• Original Assignee: Smartlight Ltd.
• Inventors: Levi, Benzion, Inbar, Dan, Wolf, Hanan
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Dudek, James A.
• Application Number:
  US08/648,007
• Time in Patent Office: 739 Days
• Field of Search: 349/5, 349/6, 40/361, 40/363
• US Class Current: 349/5
• CPC Class Codes: G02B 27/026 and a display device, e.g. CRT, LCD, for adding markings or signs or to enhance the contrast of the viewed object
• CPC Class Codes: G02F 1/13306 Circuit arrangements or driving methods for the control of single liquid crystal cells G02F1/132, G02F1/133382 take precedence
• CPC Class Codes: G02F 1/13318 Circuits comprising a photodetector
• CPC Class Codes: G02F 1/13336 Combining plural substrates to produce large-area displays, e.g. tiled displays

Abstract

A transparency viewing device including a faceplate adapted for mounting at least one transparency thereon, a passive Matrix LCD array comprising a plurality of row electrodes and a plurality of column electrodes separated by liquid crystal material, one of said plurality of electrodes having N electrodes and the other of said plurality of electrodes having M electrodes whereby the intersections of the row and column electrodes define a matrix of M×N pixel elements arranged in rows and columns, which pixels are excited by an RMS voltage difference between the two electrodes intersecting a pixel and a driver which electrifies the row and column electrodes such that at least one of a plurality n of the N electrodes or a plurality m of the M electrodes are identically electrified, wherein n≦N and m≦M.

Claims

1. A transparency viewing device comprising:

a faceplate adapted for mounting at least one transparency thereon;

a source of back lighting;

a passive matrix LCD array situated intermediate the source of back lighting and the faceplate and comprising a plurality, N, of row electrodes and a plurality, M, of column electrodes separated by liquid crystal material, wherein the intersections of the row and column electrodes define a matrix of N×

M pixel elements arranged in N rows and M columns, which pixels can be excited by a voltage difference between the two electrodes intersecting a pixel; and

a driver which substantially identically electrifies a plurality of row electrodes which drive identical patterns of pixels, and which substantially identically electrifies a plurality of column electrodes which drive identical patterns of pixels, wherein each of said patterns of pixels includes at least one pixel which is to be activated and wherein at least some of the plurality of row electrodes and some of the plurality of column electrodes are not contiguous.

2. A transparency viewing device according to claim 1 wherein each of the patterns of pixels also includes at least one pixel which is not to be activated.

3. A transparency viewing device according to claim 1 wherein one of the plurality of substantially identically electrified row electrodes and one of the plurality of substantially identically electrified column electrodes has a pattern of pixels including at least one pixel which is not to be activated and wherein one of the plurality of substantially identically electrified row electrodes and one of the plurality of substantially identically electrified column electrodes has a pattern of pixels all of whom are to be activated.

4. A transparency viewing device according to claim 1 wherein the row electrodes are electrified in two groups, each group having all those row electrodes which drive identical patterns of pixels.

5. A transparency viewing device according to claim 1 wherein the column electrodes are electrified in two groups, each group having all those column electrodes which drive identical patterns of pixels.

6. A transparency viewing device according to claim 1 wherein all of the row electrodes which intersect pixel elements which are to be excited and pixel elements which are not excited are substantially identically electrified and wherein all of the column electrodes which intersect pixel elements which are to be excited and pixel elements which are not excited are substantially identically electrified.

7. A transparency viewing device according to claim 1 wherein said voltage difference at each of the pixel elements is an RMS voltage difference having only one of two values.

8. A transparency viewing device according to claim 7 wherein the ratio of the two values is greater than 3.

9. A transparency viewing device according to claim 7 wherein the ratio of the two values is greater than 5.

10. A transparency viewing device according to claim 7 wherein the ratio of the two values is greater than 50.

11. A transparency viewing device according to claim 7 wherein one of the values is substantially equal to zero.

12. A transparency viewing device according to claim 1 wherein the electrification of at least one of the N electrodes is substantially identical to the electrification of one of the M electrodes.

13. A transparency viewing device according to claim 1 wherein at least some of the substantially identically electrified row electrodes are not continuous.

14. A transparency viewing device according to claim 13 wherein at least some of the substantially identically electrified column electrodes are not contiguous.

15. A transparency viewing device according to claim 1 wherein at least some of the substantially identically electrified column electrodes are not contiguous.

16. A transparency viewing device according to claim 1 wherein at least some of the substantially identically electrified column electrodes are not contiguous.

17. A transparency viewing device according to claim 1 wherein the excitation of the electrodes comprises pulsed voltages.

18. A transparency viewing device according to claim 1 wherein the pixel elements are transparent in the absence of an exciting voltage.

19. A transparency viewing device according to claim 1 wherein the distance between adjoining electrodes is substantially less than the width of the electrodes and further comprising a second passive LCD array underlying said first array.

20. A transparency viewing device according to claim 19 wherein the second LCD array comprises a matrix of pixel elements which are offset from the matrix of pixel elements of the overlying array.

21. A transparency viewing device according to claim 19 wherein the angular dependence of the transmission of the LCD array is a function of the viewing angle relative to a reference angle and wherein the underlying array is oriented with its reference angle at an angle different from that of the overlying array.

22. A transparency viewing device according to claim 21 wherein the reference angles of the overlying and underlying arrays are oriented at a 180°

to each other.

23. A transparency viewing device comprising:

a faceplate adapted for mounting at least one transparency thereon;

a source of back lighting;

a passive matrix LCD array situated intermediate the source of back lighting and the faceplate and comprising a plurality, N, of row electrodes and a plurality, M, of column electrodes separated by liquid crystal material, wherein the intersections of the row and column electrodes define a matrix of N×

M pixel elements arranged in N rows and M columns, which pixels can be excited by a voltage difference between the two electrodes intersecting a pixel; and

a driver which substantially identically electrifies, using a non-scanning mode, those row electrodes which drive identical patterns of pixels, and which substantially identically electrifies, using a non-scanning mode, those column electrodes which drive identical patterns of pixels.

24. A transparency viewing device according to claim 23, wherein each of said patterns of pixels includes at least one pixel which is to be activated and one pixel which is not to be activated.

25. A transparency viewing device according to claim 23 wherein one of the plurality of substantially identically electrified row electrodes and one of the plurality of substantially identically electrified column electrodes has a pattern of pixels including at least one pixel which is not to be activated and wherein one of the plurality of substantially identically electrified row electrodes and one of the plurality of identically electrified column electrodes has a pattern of pixels all of whom are to be activated.

26. A transparency viewing device according to claim 23 wherein the row electrodes are electrified in two groups, each group having all those row electrodes which drive identical patterns of pixels.

27. A transparency viewing device according to claim 23 wherein the column electrodes are electrified in two groups, each group having all those column electrodes which drive identical patterns of pixels.

28. A transparency viewing device according to claim 23 wherein all of the row electrodes which intersect pixel elements which are to be excited and pixel elements which are not excited are substantially identically electrified and wherein all of the column electrodes which intersect pixel elements which are to be excited and pixel elements which are not excited are substantially identically electrified.

29. A transparency viewing device according to claim 23 wherein said voltage difference at each of the pixel elements is an RMS voltage difference having only one of two values.

30. A transparency viewing device according to claim 29 wherein the ratio of the two values is greater than 3.

31. A transparency viewing device according to claim 30 wherein the electrification of at least one of the N electrodes is substantially identical to the electrification of one of the M electrodes.

32. A transparency viewing device according to claim 29 wherein the ratio of the two values is greater than 5.

33. A transparency viewing device according to claim 29 wherein the ratio of the two values is greater than 50.

34. A transparency viewing device according to claim 29 wherein one of the values is substantially equal to zero.

35. A transparency viewing device according to claim 23 wherein the electrification of at least one of the N electrodes is substantially identical to the electrification of one of the M electrodes.

36. A transparency viewing device according to claim 23 wherein at least some of the substantially identically electrified row electrodes are not contiguous.

37. A transparency viewing device according to claim 23 wherein at least some of the substantially identically electrified column electrodes are not contiguous.

38. A transparency viewing device according to claim 23 wherein the excitation of the electrodes comprises pulsed voltages.

39. A transparency viewing device according to claim 23 wherein the pixel elements are transparent in the absence of an exciting voltage.

40. A transparency viewing device according to claim 23 wherein the distance between adjoining electrodes is substantially less than the width of the electrodes and further comprising a second passive LCD array underlying said first array.

41. A transparency viewing device comprising:

a faceplate adapted for mounting at least one transparency thereon;

a source of back lighting;

a passive matrix LCD array situated intermediate the source of back lighting and the faceplate and comprising a plurality, N, of row electrodes and a plurality, M, of column electrodes separated by liquid crystal material, wherein the intersections of the row and column electrodes define a matrix of N×

M pixel elements arranged in N rows and M columns, which pixels can be excited by a voltage difference between the two electrodes intersecting a pixel; and

a driver which substantially identically electrifies at least one row electrode and one at least one column electrode resulting in an effective null RMS voltage across at least one pixel element.

42. A transparency viewing device according to claim 41 wherein the at least one row electrode includes a plurality of row electrodes.

43. A transparency viewing device according to claim 42 wherein at least some of the substantially identically electrified row electrodes are not contiguous.

44. A transparency viewing device according to claim 41 wherein the at least one column electrode includes a plurality of column electrodes.

45. A transparency viewing device according to claim 44 wherein at least some of the substantially identically electrified column electrodes are not contiguous.

46. A transparency viewing device according to claim 41 wherein the electrification of at least one of the N electrodes is substantially identical to the electrification of one of the M electrodes.

47. A transparency viewing device according to claim 41 wherein at least some of the substantially identically electrified column electrodes are not contiguous.

48. A transparency viewing device according to claim 41 wherein the excitation of the electrodes comprises pulsed voltages.

49. A transparency viewing device according to claim 41 wherein the pixel elements are transparent in the absence of an exciting voltage.

50. A transparency viewing device according to claim 41 wherein the distance between adjoining electrodes is substantially less than the width of the electrodes and further comprising a second passive LCD array underlying said first array.